Timed vacuum delivery belts

ABSTRACT

Thermoplastic bags delivered from the reciprocating sealing head of an intermittently operated bag making machine become immediately engaged with driven perforate vacuum belts which move at the highest velocity of the web. A vacuum box under the upper flight of each belt is provided with an elongate slot underlying each of two rows of spaced groups of perforations in the belt. Pressure differential between the upper and lower surfaces of the web maintains the web gripped to the belts, which are positively driven. Due to the relative velocities of the web and vacuum belts, the leading edge of the web is pulled forward to smooth out any wrinkles and thereafter maintains the web planar until it is transversely sealed and severed to complete one bag. By this time the leading edge of the bag has been accurately positioned relative to the clamp arms of an associated wicket stacker by the vacuum belts, and the smoothed out bag is in position for accurate transfer by the wicket stacker onto wicket pins. The vacuum is automatically controlled by the vacuum belts to eliminate mechanical valving.

United States Patent Hook Apr. 23, 1974 TIMED VACUUM DELIVERY BELTS [57] ABSTRACT [76] Inventor: Corey T. Hook, 1320 S. Clay St., I

Green Bay, Wis. 54301 Thermoplastic bags delivered from the reciprocating Filed Mar 16 1973 sealing head of an intermittently operated bag making Appl. No.: 342,120

Related U.S. Application Data Continuation-impart of Ser. No. 284,195, Aug. 28, 1972.

U.S. Cl. 93/33 H, 93/8 R, 93/93 R,

93/93 HT, 271/74 Int. CL, B31b 23/02, B31b 1/12 Field of Search 93/8 R, 93 DP, 33 H, 93 R 93/93 HT; 198/184; 27l/74 Primary ExaminerRoy Lake Assistant Examiner-James F. Coan Attorney, Agent, or FirmC. E. Tripp machine become immediately engaged with driven perforate vacuum belts which move at the highest velocity of the web. A vacuum box under the upper flight of each belt is provided with an elongate slot underlying each of two rows of spaced groups of perforations in the belt. Pressure differential between the upper and lower surfaces of the web maintains the web gripped to the belts,- which are positively driven. Due to the relative velocities of the web and vacuum belts, the leading edge of the web is pulled forward to smooth out any wrinkles and thereafter maintains the web planar until it is transversely sealed and severed to complete one bag. By this time the leading edge of the bag has been accurately positioned relative to the clamp arms of an associated wicket stacker by the vacuum belts, and the smoothed out bag is in position for accurate transfer by the wicket stacker onto wicket pins. The vacuum is automatically controlled by the vacuum belts to eliminate mechanical valving.

16 Claims, 11 Drawing Figures vy l6 14 22 \z W11 ac as I \1 '12 1 50 e6 -1IGH e 1! 1 "in"... sz- .4 99 '54 ,1

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liiiwmpqxmnmbo 90 MATCH SPEED.

I80 BAG HAS BEEN COMBED OUT.

SEALER CONTACT.

270 SEALER LIFT.

ATENTEUAPR 23 197 SHEET l [1F 4 1 TIMED VACUUM DELIVERY BELTS This application is a continuation in part of my pending prior application Ser. No. 284,195, filed Aug. 28, 1972.

BACKGROUND OF THE INVENTION The present invention concerns bag making and handling apparatus, more particularly the feed mechanism of a wicket stacker disclosed in U.S. Pat. No. 3,462,026. The patented wicket stacker automatically stacks groups of pre-punched bags onto pairs of holding pins known as wickets, and is coupled to the discharge end of a side-weld bag making machine, such as the machine disclosed in U.S. Pat. No. 3,663,338. Both patents are herein incorporated by reference for details which are not critical to the present invention. The bags are formed by longitudinally folding a thermoplastic web near its centerline so that one longitudinal edge is closed, and the lower longitudinal edge projects beyond the upper longitudinal'edge. This projecting edge is then punched with spaced holes-for eventual stacking, and the web is then transversely sealed and severed to form individual bags. Between the heated sealing bar which effects the transverse sealingand severance of the web, and the patented wicket stacker, the bags are conveyed by a series of delivery belts. The present invention provides an improved conveying system in lieu of the delivery belts of the patented apparatus of U.S. Pat. No. 3,462,026.

The leading edges of a bag ejected onto the delivery belts in the prior art device tend to lift from windage and fold back. This is undesirable, because the bag is not planar for proper pickup and transfer by the clamp arms of the wicket stacker which grip the bags for stacking, is delivered out of position to the wicket stacker, and can in general cause malfunctions leading to shutdown of the machine or rejection of the bags.

One attempted solution of this problem has been to use air jets to create a downward pressure on the bags issuing from the sealing bar to force the bags toward the conveying belts. In actual practice, this solution may word when the bag machine is producing bags at an unacceptably low rate. At acceptable production rates, however, the air jets alone have proven to be substantially ineffective for their intended purpose. The reason for this seems to be that high velocity air jets can cause localized pressures less than atmospheric pressure, with the result that the bags flutter up and down on the delivery belts, and that windage will then cause the leading edges of at least some of the bags to fold rearward, or crumple. All of these conditions are detrimental to the subsequent gripping of the bags by the clamp arms of the wicket stacker because only a slight displacement of a bag from its proper position to be gripped by the clamp arms will result in a later misalignment of its apertures relative to the wicket pins.

SUMMARY OF THE INVENTION belt is driven at a mean velocity faster than the web ve-- locity in order to develop the web and draw out any wrinkles while maintaining the web planar. A further feature is that the perforate belt is provided with interrupted groups of perforations to automatically control the application of the vacuum gripping action. Yet another aspect is that the perforate belt is mounted between and driven in timed relation to a wicket stacker and a bag machine to deliver finished bags for-pickup and transfer by the wicket stacker between a precisely located pickup position and an invariable stacking position where the bags are stacked on wickets.

In accordance with an adjustment feature, laterally alighed perforate conveying belts, each having spaced groups of perforations, have their upper flights extending over individual vacuum boxes, and any selected number of vacuum boxes can be grouped to accommodate different sizes of bags.

In accord with the basic concept of the present invention, the utility is not considered to be limited to the specific bag machine and wicket stacker herein disclosed as one embodiment, or to horizontal operation. In particular, the present invention is useful with vertical form, fill and seal machines wherein a descending web is formed into a tube and is then transversely sealed and severed to form individual packages. Thus, an important feature is that the present inventionprovides means for developing any web or web-like material downstream of a web sealing means and/or web draw rolls, or the like, especially in high speed machines wherein the web downstream of the draw rolls or sealing head is usually not under positive control, and where windage acting on the rapidly moving web tends to interfere with proper web development.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic longitudinal section, partly broken away, of the discharge end of a bag machine, a rotary wicket stacker, and the intermediately located timed vacuum delivery belts of the present invention.

plan indicated by lines 3-3 FIG. 11 is a diagrammatic perspective of the major drive components, including the discharge end of a bag machine, and the transfer carriage of a wicket stacker.

DESCRIPTION OF THE PREFERRED EMBODIMENT The discharge end of a typical side weld bag machine 10 (FIG. 1) such as the machine disclosed in U.S. Pat. No. 3,663,338, includes a pair of counterrotating feed rolls 12 which transport a folded thermoplastic film web W in the direction of the arrow 14 between upper and lower stripping fingers 16. The web W is supplied with a longitudinal fold so that one longitudinal side is closed and the opposite side has laterally staggered free edges. In the usual manner, the stripper fingers extend downstream in notched portions of the feed rolls 12 to prevent the folded web from wrapping around the feed rolls.

Immediately downstream of the feed rolls a vertically reciprocating heated sealing bar 20 cooperates with an anvil or seal roll 22 to press downward against the folded web, and transversely seal and sever the web after one bag width has been advanced by the feed rolls. A completed bag B (FIG. 2) has a folded, closed edge 24, severed and sealed side edges 26, and a top or front panel 28 which is shorter than a bottom or rear panel 30. Bottom panel 30 is provided with previously punched apertures 32 which later index with and receive two wicket pins 34 (FIG. 1).

Spaced downstream from the sealing bar 20 is a rotary wicket stacker 36, of the type disclosed in the aforementioned U.S. Pat. No. 3,462,026, which includes two lateral frame plates 38 (only one being shown) that are secured to the bag machine 10. As is disclosed in detail in the patent, the wicket stacker comprises a continuously revolving carriage C carrying several clamp units 40 which are in aligned pairs straddling the position in which a bag is completed when the sealing bar 20 seals and severs the developed web. The carriage C operates in timed relation to the bag machine 10, as will be later described in connection with FIG. 11. Each clamp unit 40 is arranged to index with and grasp a bag delivered thereto by an intermediate, timed vacuum belt conveyor 44 which is the subject of the present invention. When cam-actuated movable clamp jaws 46 of a lateral pair of the clamp units 40 are aligned with a bag, the jaws 46 rotate about the axes of elongate hinge pins 48 to clamp the lateral edges of the bag against fixed clamp jaws 50. After several successive bags have .been gripped by the clamps 40 and transferred by the carriage C in the direction of the arrow 52, the bag apertures 32 (FIG. 2) of the initial bag become vertically aligned and are guided onto the two upstanding wicket pins 34. After a predetermined number of bags are placed on the wicket pins, the wicket and the stack of bags are removed and a new wicket is positioned to accumulate another stack of bags;

In the manner disclosed in the previously identified patent, circular end plates 56 carry the clamp units 40 and are positionable axially upon a support axle 58 to accommodate different sizes of bags; The sizes referred to are the top to bottom dimension of a side weld bag, indicated by the dimension line X on FIG. 2. Since the conveyor 44 must allow access to the lateral edges of the bags by the clamp units, provision is made in the conveyor of the patented structure for a width adjustment to handle various depths of bags.

It has been found in actual practice that proper timing between the bag making machine and the wicket stacker 36 is not enough, with ordinary bag conveying means, to ensure that a bag gripped and conveyed by the carriage C will later be in exact alignment with the wicket pins 34, because the leading edge or corner of a bag may crumple, or fold back on the remainder of the bag due to windage, and thus either misalign or cover an aperture 32. When the bag is eventually brought down toward the wicket pins, the pins strike either a covered aperture or the body of the bag adjacent its apertures and cause the bag to be pulled out of the clamping jaws. This is an obviously undesirable condition since it can result in a short count for that stack of bags, necessitate stopping the machine to clear the free bag, or have other adverse effects.

It has previously been proposed to use overhead air jets to force the leading edges of the bags onto the conveyor as the bags move out from under the sealing bar 20. In operation, however, both of the above described malfunctions may occur because the bags tend to flutter under some conditions of jet pressure and rapid production rates. When the bag lip flutters and is not planar, the clamp arms cannot grip the bag in the proper transfer position, and fluttering may also lift the leading edge of the bag so that it encounters windage.

The above outlined malfunctions are positively eliminated by the conveyor 44 of the present invention, one feature of which concerns structure for maintaining exact timing of the conveying means relative to the bag machine and the wicket stacker, and for achieving later positive location of the bag by engaging the web with vacuum belt conveying means during development of the web between the sealing bar 20 and the bag clamp units 40. A further feature is that the conveying means can be conveniently adjusted as to width for handling any size of bag which can be handled by the wicket stacker. Another feature is that the vacuum is automatically controlled by the vacuum belt without the need of mechanical valving.

Driving power for the timed vacuum belt conveyor 44 is taken from a continuously driven shaft 60, of the bag machine 10, which as later described has timing relation with the sealing bar 20 and the feed rolls'12. A chain and sprocket drive train 62 transmits power to a sprocket shaft 64 that is journalled in the bearings, not shown, of pendant support straps 66 mounted on the side plates 38. Secured to the driven sprocket shaft 64 are a series of sprocket drums 68 (FIG. 4) having generally conical sprocket teeth 70. Each sprocket drum drives a perforate vacuum belt 72 having three rows of apertures, the apertures 74 of the center row being continuous and engaged with the sprocket teeth to cause positive movement of the vacuum belt in timed relation with the bag machine 10 and the wicket stacker 36. The outer two longitudinal rows of apertures 76 are in laterally aligned groups and may form, for example, three longitudinally spaced series of apertures in each vacuum belt according to the dimensional requirement of a specific machine. The important point is that the rows of vacuum apertures 76 are interrupted and have a certain timing relation to the other components, as will presently be explained.

The upper flight of each vacuum belt 72 is trained over idler rollers 78 and 80 (FIG. 1) that extend between and are rotatably mounted in spaced side plates 82 and 84. Asshown in FIGS. 3 and 4, the side plates associated with adjoining vacuum belts are in abutting relation, but are not interconnected, so as to allow relative pivotal movement therebetween. With reference to FIG. 1, each of the side plates 82 and 84 is provided with an apertured ear portion 86 that is mounted for support on a fixed pivot rod 88 extending across the bag machine 10. Support for the other end of each pairof side plates 82 and 84 isby means of a hook 90 that is pivotally mounted on a tie rod 92 (FIG. 3) which interconnects the side plates, and hangs from the axle 58 of the carriage C. A later mentioned vacuum box 94 interconnects each pair of side plates whereby the whole comprises a rigid vacuum box assembly 96.

The purpose of the described side plate mounting is to allow each vacuum box assembly 96 to be lowered,

by unlatching the hook 90 from the axle 58, until the assembly rests on a stop bar 98 as shown in phantom outline in FIG. 1. In this position the vacuum belt 72 is slack and the upper flight thereof is below the conveying path of the bags. The vacuum box assembly 96 can then be slid along the pivot rod 88. Thus, in order to reduce the width of the conveyor 44, the outer vacuum box assembly 96 is moved as described to the lateral position shown at 100, FIG. 3, and the circular end plates 56 plus the remaining vacuum box assemblies are repositioned to operative position relative to the new bag size. The belt may be removed from the inactive vacuum box assembly, and the assembly can either rest upon the stop bar 98, or its hook 90 can be suspended from the projection portion of the axle 58.

For positive frictional contact of the bags B with the upper flights of the vacuum belts 72, each vacuum box 94 which connects the side plates 82 and 84 is closed except for a slotted top wall 102 and a vacuum conduit 104 in its lower wall 106. A flexible vacuum hose 107 connects each vacuum box to an adjacent manifold which is evacuated by a conventional vacuum'pump, neither of which is shown.

An elongate slot 108 (FIG. 3) is formed in the top wall 102 of each vacuum box 94 under each of the outer interrupted rows of perforations 76 in the vacuum belt 72, in straddling relation with the continuous row of perforations 74 which engage the sprocket teeth 70. Thus, as the vacuum belt apertures 76 traverse the slots 108 with a bag supported by the belts, the pressure differential between atmospheric pressure on the upper surfaces of the bag and a lower pressure on the undersurface of the bag holds the bag down on the vacuum belts. It will be noted that the slots 108 do not extend the total length of the vacuum boxes 94, and begin in close proximity to the end nearest the sealing bar 20. As will be presently explained, the described structure and its mode of operation has proven to overcome the previously noted adverse effects of windage which in other devices has caused the malfunctions previously mentioned.

FIGS. 5-10 diagrammatically illustrate the principles of the present invention as applied to an installation for handling bags about inches wide, the dimension Y on FIG. 2. The drifeshaft 60 (FIG. 1) continuously rotates, once per sealing stroke of the sealing bar 20, and the chain and sprocket drive train 62 operates the sprocket drum 68 at a 3:1 ratio relative to the driveshaft 60. Thus, by providing the proper timing and a sprocket drum 68 with a circumference of 10 inches, and by providing a vacuum belt 72 which is 60 inches long and has two equally spaced groups of the apertures 76, one group of apertures will index with each bag length of web material advanced from the sealing bar 20. Each group of apertures 76 extends for about 7 r inches along the vacuum belt for handling a bag 10 inches wide.

The web material is advanced intermittently from the feed rolls l2, and the velocity of the vacuum belt is the same as the maximum velocity of the web material. Consequently, the vacuum belt will initially accelerate relative to the web, then match the web velocity, and then continue to accelerate relative to the web because the web slows down before again stopping for a sealing and severing operation.

FIG. 11 diagrammatically illustrates the major drive components for synchronizing operation of the bag machine 10, the timed vacuum belt conveyor 44, and the wicket stacker 36. The driveshaft 60 of the bag machine is continuously driven from a motor M by a cog belt and pulley drive unit 110. Power from he driveshaft 60 is applied to the axle 58 of the wicket stacker 36 via a cog belt and pulley drive unit 112, and to the sprocket shaft 64 of the timed vacuum belt conveyor 44 by the chain and sprocket drive train 62.

In order to provide intermittent rotation of the draw or feed rolls 12, the continuous torque of the driveshaft 60 is intermittently applied to the draw rolls through an electrically operated clutch 114 and an electrically operated brake 116. Both the clutch and brake are mounted on a shaft assembly 118 and controlled by cam-driven switches, not shown, having timed relation with the driveshaft 60. A cog belt and pulley drive train 120 couples the output end of the shaft assembly 118 to the lower one of the draw rolls 12. The two draw rolls are geared together to counterrotate.

The output end of the driveshaft 60 carries a crank pin 122, the eccentricity of which relative to the driveshaft 60 can be adjusted while the bag machine is in operation. The crank pin 122 and a crank pin 124, on

a pivotable gear segment 126, are coupled by a crank arm 128 to thereby oscillate the gear segment. Meshed with the gear segment is a gear train 130 transmitting power to oscillate the input end of the clutch 114.

In order to drive the draw rolls 12 in a single direction, with intermittent motion, the clutch 114 is electrically controlled to drive the shaft assembly 118 only in a counterclockwise direction as viewed in FIG. 11. Between successive movements of the output end of the shaft assembly 118, the electrically controlled brake 116 arrests the same. With the described drive train system, the timed vacuum belts 72 and the wicket stacker carriage C aer continuously driven in timed relation with the bags delivered by the intermittently operated draw rolls 12.

In FIG. 5, the leading edge of an unfinished bag B is aligned with the center of the seal roll 22 and no vacuum apertures 76 are yet exposed along; the upper flight of the vacuum belt 72. In one bag producing cycle assumed to begin and end at 360 of the shaft 60, at 0 (FIG. 5) the feed rolls 12 begin tofeed one bag width of web material toward the revolving wicket stacker carriage C. At about 15 in the cycle (FIG. 6), the leading edge of the bag comes in contact with the first open vacuum apertures 76, one group of said apertures at this time just passing over the idler rollers 78 (FIG. 1) and being in communication with the vacuum source through the vacuum box slots 108. Accordingly, the leading edge of the web is immediately flattened, forced against the belts, and then dragged out to its full development length.

At in the cycle (FIG. 7) the vacuum belts are no longer accelerating relative to the web, but of course remain in timed relation to the other components of the bag machine and continue to develop the web. At this time the web velocity and the belt velocity are the same, and one longitudinal half of the vacuum apertures 76 are masked by the web, and the other half are uncovered. Web development continues to about of the cycle (FIG. 8) and the brake 116 (FIG. 11) arrests the feed rolls 12. At 210 (FIG. 9) the sealing bar 20 (FIG. 1) descends to heat seal and sever the web and form an individual bag B. Meanwhile, all of the vacuum belt apertures 76, beginning at 180 in the cycle, have advanced beyond the leading edge of the bag so that the vacuum-induced gripping force on the bag is eliminated, and the continuously moving clamp unit 40 which is to pick up this bag is ascending; toward a horizontal bag-pickup position.

Between about 240300 in the cycle, depending upon the adjusted dwell time of the sealing bar 20 (shown as 270 in FIG. 10), the sealing bar rises and the moving clamp unit 40 grasps the bag and lifts it from the vacuum belts 72 for transport to the wicket pins 34. At 360 or (FIG. the bag is completely out of the path of the incoming web now being advanced by the feed rolls 12 toward the wicket stacker carriage C for another actuation of the clutch 114 (FIG. 11) and a repetition of the cycle just completed with another series of vacuum apertures 76.

It should be noted that more and more vacuum belt apertures 76 leave communication with the vacuum .box assemblies 96 as the bag approaches full development at 180. Thus, only one half of the bag cycle causes any influx of atmospheric air, and the vacuum requirement is substantially nothing from MO -360", or half of the cycle. It will be apparent, therefore, that an important feature of the present invention is that positive control of the bag isachieved for delivery to the clamp arms in unwrinkled condition and in timed relation, and that the spaced groups of apertures 76, plus the bag, control the vacuum without the necessity of any mechanical valving.

From the preceding description, it is apparent that the interrupted series of vacuum belt apertures 76, and their movement across the vacuum boxes 94 in timed relation with the stacker carriage C, the sealing bar 20,

and the feed rolls 12, provides (1) planar retention of the web, (2) positive gripping action with relatively little vacuum, (3 positive prevention against the adverse effects of windage, (4) a slight tensioning of the web to draw out wrinkles and keep it planar, (5) accurately timed and positioned finished bags for pickup by the clamp units 40, and (6) the desired end result of delivering the bags in planar condition and in precise registry to the stacking pins of the wicket 34.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

What is claimed is: g

1. In a web handling machine including intermittently driven means for feeding a web along a predetermined path toward adjacent web handling means at speeds increasing to and decreasing from a predetermined maximum speed, means intermediate said feeding and handling means for maintaining the planarity of the web, said latter means comprising a vacuum belt having a group of perforations in a perforate and planar transport reach disposed parallel to the path of movement of the web, a' vacuum box contacting said transport reach and having an elongated slot arranged to communicate with saidgroup of perforations to provide a vacuum gripping of the web against said planar transport reach, and drive means for driving said vacuum belt in timed relation with said intermittent web feeding means and at a speed at least equal to said predetermined maximum speed and at times in excess of said maximum web speed for causing said vacuum conveyor to slide relative to the web while pulling the vacuum gripped portion of the web in a taut unwrinkled condition unaffected by windage.

2. Apparatus according to claim 1, wherein said drive means continuously drives said belt in timed relation to said web feeding means and at a speed equal to said predetermined maximum web speed.

3. In a web handling machine including intermittently operable means for feeding a web toward adjacent web handling means, means intermediate said feeding and handling means for maintaining the. planarity of the web, said latter means comprising a driven belt having discontinuous perforations and a planar transport reach having an elongated slot arranged to communicate with said perforations to provide a vacuum gripping of the web against said planar transport reach, means for driving said belt in timed relation to said web feeding means, said perforations being aligned with said elongated slot and being discontinuous along the length of said belt, said belt further including a row of continuous sprocket perforations, a sprocket having teeth engaged with said sprocket perforations, and means coupling said drive means to said sprocket.

4. Apparatus according to claim 3 wherein the belt perforations aligned with said elongate slot are in equally spaced groups, said vacuum box being continubelt portions moving across said vacuum box start and vstop the vacuum gripping of the web.

5. In a web handling machine including a pair of intermittently driven rolls in gripping engagement with a web having a leading portion with a leading edge and for feeding the web toward an adjacent web handling station, means intermediate said web handling station and said driven rolls for transporting the web in planar condition to said handling station, said means comprising a perforate endless belt having a flight coincident with the plane of the web and perforations extending in a row along said flight, a vacuum box having an elongate slot underlying said perforations to provide a vacuum gripping of the leading portion of the web, and means for driving said belt in timed relation to said intermittently driven rolls at a linear velocity substantially equal to the highest peripheral velocity of said driven rolls for inducing slippage between said belt and the vacuum gripped leading portion of the web for pulling said gripped portion against the resistance of said rolls and providing a wrinkle free leading portion.

6. Apparatus according to claim 5 and additionally comprising means for severing said leading portion from the web at a point upstream of said driven rolls, wherein said belt communicates with said slot to vacuum grip the leading edge of the web while the web is advanced by said driven rolls, and wherein said belt advances at a mean velocity faster than the web velocity to induce slippage relative to the web for developing the web planar and unwrinkled toward said web handling station, and wherein said perforations move over the leading edge of said web portion prior to moving out of communication with said elongated slot to release said leading web portion prior to severing the web portion from the web.

7. In a web handling machine including a pair of in termittently-driven rolls in gripping engagement with a web for feeding the web toward an adjacent web handling station, means intermediate said web handling station and said driven rolls for transporting the web in planar condition to said handling station, said means comprising a perforate endless belt having a flight coincident with the plane of the web and perforations extending in a row along said flight, a vacuum box having an elongated slot underlying said perforations tp provide a vacuum gripping of the web, means for driving said belt in timed. relation to said intermittently driven rolls at a linear velocity substantially equal to the highest peripheral velocity of said driven rolls, said belt including a continuous row of perforations, a sprocket having teeth engaged with said perforations, and means coupling said driving means to said sprocket.

8. Apparatus according to claim wherein the belt perforations aligned with said elongated slot are in equally interspaced interrupted groups along the length of said belt having imperforate portions therebetween, said perforate and imperforate portions of the moving belt providing the sole means for starting and stopping the vacuum gripping of the web.

9. In a bag making machine including a pair of intermittently driven draw rolls in driving engagement with a web for feeding the web to an adjacent intermittently operated web sealing and severing station, timed bag delivery means downstream of said web sealing station for both developing the web and transporting the bags from said station comprising a perforate endless belt having an upper flight coincident with the plane of the web, said perforations being aligned in two rows along the length of said belt with one of said rows being continuous and the other of said rows being interrupted, a continuously driven sprocket having teeth engaged with the continuous row of perforations, a vacuum box underlying said flight and having an elongate slot for communication with the interrupted row of said perforations, a continuously driven rotary carriage at said transfer station, clamp means on said carriage for gripping a bag delivered to said transfer station, and means for driving said sprocket, said draw rolls and said carriage in timed relation, said belt having a velocity approximately the maximum velocity of the web engaged with said drawrolls.

10. In a bag machine including intermittently operated draw rolls in gripping engagement with a folded web for feeding the web to a sealing and severingstation; an intermittently operated sealing head at said station for transversely sealing and severing the folded web to form individual bags; a continuously operated rotary bag transfer carriage downstream of said sealing station for gripping and transferring each bag; the improvement comprising timed delivery means for transferring each bag from said sealing head to said transfer carriage, said delivery means including a perforate endless belt having an interrupted row of perforations and a continuous row of perforations, said belt having an upper flight substantially coincident with the plane of the bags delivered by said draw rolls, a vacuum box underlying said upper flight with an elongate vacuum slot aligned with the path of said interrupted row of perforations, a sprocket having teeth engaged with said continuous row of perforations, and means for continuously driving said sprocket to drive said belt at a linear velocity approximating the maximum peripheral velocity of said draw rolls, the leading perforation of said interrupted row of perforations aligning with the leading edge portion of a bag and the adjacent end of said vacuum slot so that the bag is kept planar during development and subsequent delivery to said transfer carriage.

11. In a bag handling machine including a bag transfer carriage for gripping and reorienting a bag delivered thereto; a sealing head for transversely sealing and severing a folded web to form individual bags and a pair of intermittently driven draw rolls disposed in gripping engagement with the web for feeding the web along a predetermined path through said sealing head in bag length increments; the improvement which comprises vacuum gripping means disposed between the draw rolls and the transfer carriage for slidably gripping a leading portion of the web including the leading edge, and power means for moving said vacuum gripping means along a plane coincident with the path of the web and at an average speed in excess of that of the web for pulling the web taut and flat, said power means being-effective for releasing vacuum gripping engagement between said gripping means and said leading web portion by pulling said vacuum gripping means off the leading edge of said leading portion of the web.

12. An apparatus according to claim 11 wherein said vacuum gripping means is pulled free from the leading edge after a bag length has been moved into position to be sealed and severed.

13. An apparatus according to claim 12 wherein said vacuum gripping means is pulled free from said leading edge prior to sealing and severing the web.

14. An apparatus according to claim 11 wherein said vacuum gripping means is a perforated portion of an endless vacuum belt.

15. An apparatus according to claim 14 and additionally comprising means defining an evacuated vacuum chamber having an elongated slot therein disposed in position for flow communication with the perforated portion of said endless vacuum belt when said perforated portion is aligned therewith, said perforated por tion of said belt moving out of communication with said slot after said perforated portion has first moved off the leading edge of the web portion.

16. An apparatus according to claim 15 wherein said endless belt includes a plurality of evenly spaced groups of perforations therein and wherein said power means is timed with a sealing head and draw rolls to move different ones of said group of perforations into position to establish flow communication between said slot and the leading edge of the web shortly after each bag has been severed therefrom.

UNITED STATES PATENT OFFICE CERTEFECATE 0F CORRECTION PATENT NO. 3, 805,683

DATED April 23, 1974 INVENTOR(S) I COREY T. HOOK It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On first page of Letters Patent the Assignee was left out. Should be Assignee: FMC Corporation,

San Jose, Calif.

8 line 43 chane "word" to work Column 5, line 44 change "drifeshaft" to driveshaft Column 6, line 35 change "aer" to are Column 8, line 13 after "reach" insert underlying the web, a vacuum box under said transport reach Signed and Scaled this twenty-sixth Day Of August 1975 [SEAL] Attest:

RUTH C. MASON Arresting Officer 

1. In a web handling machine including intermittently driven means for feeding a web along a predetermined path toward adjacent web handling means at speeds increasing to and decreasing from a predetermined maximum speed, means intermediate said feeding and handling means for maintaining the planarity of the web, said latter means comprising a vacuum belt having a group of perforations in a perforate and planar transport reach disposed parallel to the path of movement of the web, a vacuum box contacting said transport reach and having an elongated slot arranged to communicate with said group of perforations to provide a vacuum gripping of the web against said planar transport reach, and drive means for driving said vacuum belt in timed relation with said intermittent web feeding means and at a speed at least equal to said predetermined maximum speed and at times in excess of said maximum web speed for causing said vacuum conveyor to slide relative to the web while pulling the vacuum gripped portion of the web in a taut unwrinkled condition unaffected by windage.
 2. Apparatus according to claim 1, wherein said drive means continuously drives said belt in timed relation to said web feeding means and at a speed equal to said predetermined maximum web speed.
 3. In a web handling machine including intermittently operable means for feeding a web toward adjacent web handling means, means intermediate said feeding and handling means for maintaining the planarity of the web, said latter means comprising a driven belt having discontinuous perforations and a planar transport reach having an elongated slot arranged to communicate with said perforations to provide a vacuum gripping of the web against said planar transport reach, means for driving said belt in timed relation to said web feeding means, said perforations being aligned with said elongated slot and being discontinuous along the length of said belt, said belt further including a row of continuous sprocket perforations, a sprocket having teeth engaged with said sprocket perforations, and means coupling said drive means to said sprocket.
 4. Apparatus according to claim 3 wherein the belt perforations aligned with said elongate slot are in equally spaced groups, said vacuum box being continuously evacuated so that the perforate and imperforate belt portions moving across said vacuum box start and stop the vacuum gripping of the web.
 5. In a web handling machine including a pair of intermittently driven rolls in gripping engagement with a web having a leading portion with a leading edge and for feeding the web toward an adjacent web handling station, means intermediate said web handling station and said driven rolls for transporting the web in planar condition to said handling station, said means comprising a perforate endless belt having a flight coincident with the plane of the web and perforations extending in a row along said flight, a vacuum box having an elongate slot underlying said perforations to provide a vacuum gripping of the leading portion of the web, and means for driving said belt in timed relation to said intermittently driven rolls at a linear velocity substantially equal to the highest peripheral velocity of said driven rolls for inducing slippage between said belt and the vacuum gripped leading portion of the web for pulling said gripped portion against the resistance of said rolls and providing a wrinkle free leading portion.
 6. Apparatus according to claim 5 and additionally comprising means for severing said leading portion from the web at a point upstream of said driven rolls, wherein said belt communicates with said slot to vacuum grip the leading edge of the web while the web is advanced by said driven rolls, and wherein said belt advances at a mean velocity faster than the web velocity to induce slippage relative to the web for developing the web planar and unwrinkled toward said web handling station, and wherein said perforations move over the leading edge of said web portion prior to moving out of communication with said elongated slot to release said leading web portion prior to severing the web portion from the web.
 7. In a web handling machine including a pair of intermittently driven rolls in gripping engagement with a web for feeding the web toward an adjacent web handling station, means intermediate said web handling station and said driven rolls for transporting the web in planar condition to said handling station, said means comprising a perforate endless belt having a flight coincident with the plane of the web and perforations extending in a row along said flight, a vacuum box having an elongated slot underlying said perforations tp provide a vacuum gripping of the web, means for driving said belt in timed relation to said intermittently driven rolls at a linear velocity substantially equal to the highest peripheral velocity of said driven rolls, said belt including a continuous row of perforations, a sprocket having teeth engaged with said perforations, and means coupling said driving means to said sprocket.
 8. Apparatus according to claim 5 wherein the belt perforations aligned with said elongated slot are in equally interspaced interrupted groups along the length of said belt having imperforate portions therebetween, said perforate and imperforate portions of the moving belt providing the sole means for starting and stopping the vacuum gripping of the web.
 9. In a bag making machine including a pair of intermittently driven draw rolls in driving engagement with a web for feeding the web to an adjacent intermittently operated web sealing and severing station, timed bag delivery means downstream of said web sealing station for both developing the web and transporting the bags from said station comprising a perforate endless belt having an upper flight coincident with the plane of the web, said perforations being aligned in two rows along the length of said belt with one of said rows being continuous and the other of said rows being interrupted, a continuously driven sprocket having teeth engaged with the continuous row of perforations, a vacuum box underlying said flight and having an elongate slot for communication with the interrupted row of said perforations, a continuously driven rotary carriage at said transfer station, clamp means on said carriage for gripping a bag delivered to said transfer station, and means for driving said sprocket, said draw rolls and said carriage in timed relation, said belt having a velocity approximately the maximum velocity of the web engaged with said draw rolls.
 10. In a bag machine including intermittently operated draw rolls in gripping engagement with a folded web for feeding the web to a sealing and severing station; an intermittently operated sealing head at said station for transversely sealing and severing the folded web to form individual bags; a continuously operated rotary bag transfer carriage downstream of said sealing station for gripping and transferring each bag; the improvement comprising timed delivery means for transferring each bag from said sealing head to said transfer carriage, said delivery means including a perforate endless belt having an interrupted row of perforations And a continuous row of perforations, said belt having an upper flight substantially coincident with the plane of the bags delivered by said draw rolls, a vacuum box underlying said upper flight with an elongate vacuum slot aligned with the path of said interrupted row of perforations, a sprocket having teeth engaged with said continuous row of perforations, and means for continuously driving said sprocket to drive said belt at a linear velocity approximating the maximum peripheral velocity of said draw rolls, the leading perforation of said interrupted row of perforations aligning with the leading edge portion of a bag and the adjacent end of said vacuum slot so that the bag is kept planar during development and subsequent delivery to said transfer carriage.
 11. In a bag handling machine including a bag transfer carriage for gripping and reorienting a bag delivered thereto; a sealing head for transversely sealing and severing a folded web to form individual bags and a pair of intermittently driven draw rolls disposed in gripping engagement with the web for feeding the web along a predetermined path through said sealing head in bag length increments; the improvement which comprises vacuum gripping means disposed between the draw rolls and the transfer carriage for slidably gripping a leading portion of the web including the leading edge, and power means for moving said vacuum gripping means along a plane coincident with the path of the web and at an average speed in excess of that of the web for pulling the web taut and flat, said power means being effective for releasing vacuum gripping engagement between said gripping means and said leading web portion by pulling said vacuum gripping means off the leading edge of said leading portion of the web.
 12. An apparatus according to claim 11 wherein said vacuum gripping means is pulled free from the leading edge after a bag length has been moved into position to be sealed and severed.
 13. An apparatus according to claim 12 wherein said vacuum gripping means is pulled free from said leading edge prior to sealing and severing the web.
 14. An apparatus according to claim 11 wherein said vacuum gripping means is a perforated portion of an endless vacuum belt.
 15. An apparatus according to claim 14 and additionally comprising means defining an evacuated vacuum chamber having an elongated slot therein disposed in position for flow communication with the perforated portion of said endless vacuum belt when said perforated portion is aligned therewith, said perforated portion of said belt moving out of communication with said slot after said perforated portion has first moved off the leading edge of the web portion.
 16. An apparatus according to claim 15 wherein said endless belt includes a plurality of evenly spaced groups of perforations therein and wherein said power means is timed with a sealing head and draw rolls to move different ones of said group of perforations into position to establish flow communication between said slot and the leading edge of the web shortly after each bag has been severed therefrom. 